Structure and method for detection of physical interference during transport of an article

Abstract

A method for detecting physical interference with desired transport of an article. The method includes the step of detecting an operative acoustic signal representing the structure-borne sound pattern of an article during said article transport, and detecting the presence of interference based on the acoustic signal. A system for performing the method includes a transport device adapted to transport the article through a predetermined path and an acoustic sensor in structure-borne acoustic contact with the transport device and capable of producing an acoustic signal indicative of physical interference.

What is claimed:  
     
       1. A method for detecting physical interference with desired transport of an article, the method comprising: 
       a) detecting with an acoustic sensor an operative acoustic signal representing a structure-borne sound pattern of said article during transport; and  
       b) detecting the presence of physical interference based on said acoustic signal;  
       wherein said acoustic sensor is in structure-borne acoustic contact with said article at least during said physical interference.  
     
     
       2. The method according claim  1  wherein the acoustic sensor is in physical contact with an object that produces said physical interference. 
     
     
       3. The method according claim  2  wherein the article is transported by the transport device between stations external to the transport device and wherein step (a) includes using an acoustic sensor in physical contact with at least one of said stations. 
     
     
       4. The method according to claim  1  wherein step (a) includes using a transport device to transport said article wherein the acoustic sensor is in physical contact with the transport device. 
     
     
       5. The method according to claim  4  wherein the article is a workpiece and step (a) includes using a mechanical device as the transport device for transporting said workpiece. 
     
     
       6. The method according to claim  5  wherein the mechanical device is a robotic device. 
     
     
       7. The method according to claim  6  wherein the workpiece is a semiconductor wafer and step (a) comprises detecting the structure-borne acoustic signal representing the sound pattern generated during the transport of said wafer. 
     
     
       8. The method according to claim  7  further comprising transporting said wafer through a semiconductor process tool. 
     
     
       9. The method according to claim  8  wherein said semiconductor process tool comprises at least one of a Rapid Thermal Processing tool, an implanter, a wet bench, a clustered processing tool, a furnace, inspection equipment, bay-to-bay automated product transport, within-bay product transport, CMP equipment, lithography equipment; dry strip equipment, sputter equipment, and electroplating equipment. 
     
     
       10. The method according to claim  8  wherein step (b) further comprises detecting physical interference comprising at least one of colliding, rubbing, scratching, and slipping. 
     
     
       11. The method according to claim  8  wherein step (b) further comprises detecting physical interference comprising at least one of a collision between the wafer and another object; improper contact between the wafer and the robotic device; the wafer colliding with adjacent structure; the wafer rubbing against adjacent structure; the wafer rubbing against slots within a cassette; two portions of said robotic device rubbing against each other; a wafer dropping off said robotic device; said robotic device rubbing against a portion of said process tool; two parts of said process tool colliding with one another; and improper operation caused by accumulated debris. 
     
     
       12. The method according to claim  1  further comprising responding to said physical interference by recording the occurrence of said physical interference in an error log. 
     
     
       13. The method according to claim  1  further comprising responding to said physical interference by stopping movement of said transported article based on detection of said structure-borne acoustic signal produced by said physical interference. 
     
     
       14. The method according to claim  1  wherein step (a) includes using an accelerometer as said acoustic sensor. 
     
     
       15. A method for detecting physical interference with desired transport of an article when said article is transported by a transport device through a predetermined path, the method comprising: 
       a) storing a reference acoustic signal;  
       b) detecting a subsequent operative acoustic signal representing a structure-borne sound pattern of an article during said article transport of said article through said predetermined path;  
       c) comparing the operative acoustic signal with the reference signal; and  
       d) detecting any differences between the reference signal and the operative signal and using said detected differences to determine the presence of interference during said transport.  
     
     
       16. The method according to claim  15 , wherein step (a) further comprises detecting a baseline acoustic signal representing a sound pattern generated during transport of a sample article through said predetermined path without any physical interference and storing said baseline acoustic signal as said reference acoustic signal. 
     
     
       17. The method according to claim  15  wherein step (b) includes using an acoustic sensor in physical contact with the transport device. 
     
     
       18. The method according to claim  17  wherein step (b) includes using an accelerometer as said acoustic sensor. 
     
     
       19. The method according to claim  15  wherein step (a) further includes detecting a plurality of acoustic signals representing structure-borne sound patterns generated during transport of a plurality of sample articles through said predetermined path without any physical interference, and storing an average of said plurality of structure-borne acoustic signals as said reference acoustic signal. 
     
     
       20. The method according to claim  19  further comprising establishing a predetermined acceptable deviation from the reference acoustic signal and producing an error signal whenever comparing the operative acoustic signal with the reference acoustic signal reveals a difference therebetween in excess of the acceptable deviation between said reference acoustic signal and said operative acoustic signal. 
     
     
       21. The method according to claim  15  wherein step (b) includes detecting and storing an amplitude and a frequency spectrum of said signal. 
     
     
       22. The method according to claim  21  wherein step (a) includes storing both an amplitude and a frequency spectrum of said reference signal, step (b) includes detecting both an amplitude and a frequency spectrum of said operative acoustic signal, and wherein step (c) includes comparing the frequency spectrum of the operative acoustic signal to the frequency spectrum of the reference acoustic signal. 
     
     
       23. The method according to claim  22  further including the step of identifying specific acoustic signal frequency spectra corresponding to specific physical interferences and wherein step (c) includes comparing the operative acoustic signal frequency spectrum with the identified specific acoustic signal frequency spectra corresponding to specific physical interferences, to identify the physical interference giving rise to the operative acoustic signal. 
     
     
       24. The method according to claim  15  wherein the reference signal comprises identified specific acoustic signal frequency spectra corresponding to specific physical interferences and wherein step (c) includes the step of comparing the operative acoustic signal frequency spectrum with the identified specific physical interference frequency spectra to identify the physical interference giving rise to the operative acoustic signal. 
     
     
       25. A system adapted to detect physical interference with desired transport of an article, the system comprising: 
       a) a transport device adapted to transport the article through a predetermined path; and  
       b) an acoustic sensor capable of producing an acoustic signal indicative of said physical interference, wherein said acoustic sensor is in structure-borne acoustic contact with said article at least during said physical interference.  
     
     
       26. The system according to claim  25  wherein said acoustic sensor is in physical contact with said transport device. 
     
     
       27. The system according to claim  25  wherein said acoustic sensor is in physical contact with an object that produces said physical interference. 
     
     
       28. The system according to claim  25  further comprising: 
       c) a controller programmed to store a baseline acoustic signal from said acoustic sensor representing a structure-borne sound pattern generated during the transport of a sample article through said predetermined path without physical interference; to receive an operative acoustic signal from said acoustic sensor representing the structure-borne sound pattern of an article during its transport through said predetermined path; to compare the operative acoustic signal with the baseline signal; and to detect any differences between the baseline signal and the operative signal and use said detected differences to identify said physical interference.  
     
     
       29. The system according to claim  25  wherein said transport device is a mechanical handling device. 
     
     
       30. The system according to claim  29  wherein said mechanical handling device is a robotic handling device. 
     
     
       31. The system according to claim  30  wherein said robotic handling device is a first element of a semiconductor processing tool and said article is a semiconductor wafer being handled by said robotic handling device. 
     
     
       32. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for detecting physical interference with desired transport of an article when said article is transported by a transport device through a predetermined path, said method steps comprising: 
       inputting and storing a baseline acoustic signal representing a structure-borne sound pattern generated during the transport of a sample article through said predetermined path without any physical interference;  
       inputting an operative acoustic signal representing a structure-borne sound pattern of an article during transport of said article through said predetermined path;  
       comparing the operative acoustic signal with the baseline signal; and  
       detecting any differences between the baseline signal and the operative signal and using said detected differences to identify said physical interference.